Rebalancing a portfolio means bringing your investments back to the target mix of stocks, bonds, and other assets you chose in your investment plan. Over time, market returns push that mix out of balance: a strong stock year can turn a 60/40 stock-and-bond portfolio into a 70/30 one, quietly raising your risk. Rebalancing is the routine maintenance that restores your intended allocation, and it is one of the few portfolio decisions you can control.
Why rebalancing matters
Your asset allocation is the biggest driver of your portfolio's risk and return. If you set a 60% stock, 40% bond target because it matches your time horizon and comfort with volatility, letting it drift to 80% stocks means you are now taking more risk than you planned. Rebalancing also enforces a disciplined "sell high, buy low" habit: you trim the assets that have grown and add to the ones that have lagged, rather than chasing whatever performed best last year.
It is worth being realistic about what rebalancing does not do. Research from Vanguard has found that rebalancing is primarily a risk-control tool; it does not reliably boost long-term returns, and it can slightly reduce them in strong bull markets because you sell some stocks on the way up. The benefit is a portfolio that stays aligned with your goals and your ability to stomach downturns.
The two main rebalancing strategies
Most investors choose between two approaches, and each has trade-offs.
Calendar rebalancing
You check and rebalance on a fixed schedule, such as every January, every six months, or once a year. Calendar rebalancing is simple, easy to automate, and keeps you from tinkering constantly. The downside is that it ignores what markets are actually doing, so a portfolio can drift well past your risk tolerance between check-ins.
Threshold rebalancing
You set a band around each target, such as plus or minus 5 percentage points, and rebalance only when an asset class crosses it. Threshold rebalancing responds to real drift and can mean fewer trades in calm markets, but it requires monitoring and can trigger trades during volatile periods. Many financial planners use a hybrid: check on a schedule, and rebalance only if a band has been breached.
- Calendar: best for hands-off investors who want a predictable routine.
- Threshold: best for investors who want tighter risk control and are willing to monitor.
- Hybrid: a common middle ground that limits both drift and unnecessary trading.
How to actually rebalance your account
Once you know your target allocation and your trigger, rebalancing is mostly administrative. A practical sequence:
- List your target weights for each asset class across all accounts, such as 50% US stocks, 20% international stocks, and 30% bonds.
- Add up current values in each class and calculate the actual percentages.
- Compare to your bands and identify which classes are over or under target.
- Direct new contributions to underweight assets first. Adding money to lagging funds is often the cheapest way to rebalance.
- Use dividends and interest to buy underweight assets instead of reinvesting automatically.
- Sell only what is needed to close the remaining gap, favoring tax-advantaged accounts like a 401(k) or IRA where trades do not trigger capital gains taxes.
In taxable brokerage accounts, selling appreciated investments can create a capital gains tax bill. When possible, rebalance inside tax-advantaged accounts first, and use new cash to nudge taxable accounts back toward target. If you hold a target-date fund or a balanced fund, the fund manager handles rebalancing for you, so you generally do not need to do it yourself.
How often should you rebalance?
There is no single correct frequency, but annual or semiannual check-ins with a 5% threshold band are common and reasonable for most long-term investors. Rebalancing too often adds trading costs and, in taxable accounts, tax drag, while rarely improving outcomes. Rebalancing too rarely lets risk drift. A useful rule: review once a year, act when a band is breached, and always rebalance after a major life change such as retirement, a job change, or a shift in your risk tolerance.
Keep in mind that rebalancing is not the same as market timing. You are not predicting which asset will win next; you are restoring the mix you already decided was right for you.
What to remember
- Rebalancing restores your target asset allocation and keeps your risk in line with your plan.
- Choose calendar, threshold, or hybrid rules and write them down so you do not improvise.
- Use new contributions and dividends first to avoid unnecessary selling and taxes.
- Prioritize tax-advantaged accounts for trades that trigger gains.
- Review at least annually, and rebalance after major life changes.
